In a separate bowl, mix the flour, baking soda, baking powder, salt, and cinnamon. Stir the dry ingredients into the liquid in two stages, just until blended. Fold in the walnuts and currants (or raisins). Spoon heaping tablespoonfuls of dough onto the baking sheets, leaving 2-½ inches between each one. Bake for 15 minutes. When done, the cookies will form a crust, but they’ll still be soft to the touch. Cool on the sheets for 2 minutes, then transfer to a rack to finish cooling.